The enzymes involved in the biosynthesis of trimethylaminobutyrate from trimethyllysine in animal tissues are being purified and characterized with regard to distribution, kinetics, and regulation. The role of vitamin C in vivo in trimethyllysine hydroxylation is being investigated in guinea pigs. The mobilization of carnitine from muscle, as affected by hormones is being studied. The transport of carnitine and its precursors into various tissues is also being examined.